Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2021-01-24
Abstract： In this paper we re-investigated the relationship between the symmetry of inertial systems and the Lorentz transformation. We found that when we just follow the following three principles: (1)we can define the time in the whole space with a prescribed clock synchronization, (2)the time-space is uniform and the space is isotropic and (3)all the inertial systems are equivalent, then we can totally construct a general coordinate transformation to meet the symmetry of inertial systems, and with a special assumption on the speed of light, we can construct a non-Lorentz transformation between inertial systems to make the particle’s energy have a limited value, which is similar to the rainbow model. Similar to the usual Lorentz violating models, the non-Lorentz transformation in this paper lead to a new modified disperse relation. We applied the obtained disperse relation to analyze the photon’s arrival time lag effect in astronomy and found that the "maximum energy" derived in our model is somewhat related to the "maximum energy" assumed in the rainbow model.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2021-06-26
Abstract： In this paper we introduced a parameter n to characterize the variation of the speed of light between different inertial systems. In order to satisfy the well-known fundamental principle and not violate some reliable experiments’ results, we should impose some necessary constraints on n. Firstly and importantly, the introduction of n should be in agree with the following three principles: (1)we can define the time in the whole space with a prescribed clock synchronization, (2)the time-space is uniform and the space is isotropic and (3)all the inertial systems are equivalent, which are the inheritance of the special relativity (SR). With some constraints on n, we construct a general coordinate transformation to meet the symmetry of inertial systems. In recent years, many theories have shown the interest in the breakdown of the Lorentz invariance at ultrahigh energy scale, such as the quantum gravity, which imply that the energy of particle has a limited value (called the “Planck energy”) rather than be infinite derived from the Lorentz model. So we construct an expression for n to characterize the violation of Lorentz model. And further, by comparing with the well-known rainbow model, we found that the "maximum energy" derived in our paper is somewhat related to the "maximum energy" assumed in the rainbow model." "
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrometry Subjects: Library Science，Information Science >> Information Science Subjects: Physics >> Atomic and Molecular Physics submitted time 2021-03-05
Abstract： " Gravitational wave signals were directly detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015, bring hope to new physics and astrophysics and setting off a new wave of the development of laser interferometer gravitational wave detectors. In the background of the vigorous development of the interferometer gravitational wave detectors from ground to space, a comparative study of each detector are carried out from the aspects of construction history, technical characteristics and development positioning, and operation mode. And the experiences and enlightenments of the construction and operation of laser interferometer gravitational wave detectors are further summarized, namely: the construction of laser interferometer gravitational wave detector is a long-term project, which helps to promote the perfect development of scientific research fault tolerance mechanism and scientific evaluation mechanism; the construction of gravitational wave detector is a high-tech project, which helps to promote the coordinated development of multidisciplinary technologies; the construction of laser interferometer gravitational wave detectors is an international project, which helps to promote the healthy development of scientific research cooperation.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-28 Cooperative journals: 《天文研究与技术》
Abstract： 公众科学(citizen science)指的是非职业科学家（如科学爱好者等）组织或参与的科学研究活动，业余天文学(citizen astronomy)是公众科学的一个经典分支。受益于科技水平的提升，当代天文爱好者有力地补充了职业天文学家无力或无暇顾及的领域，如时域天文学观测、大数据的人工分析、数据挖掘等。近年来，我国业余天文学发展迅速，我国爱好者在新天体的搜寻和发现上成绩显著，但与欧美国家的业余天文相比，我国爱好者的兴趣点比较单一，对长期监测、数据挖掘等项目的参与度低。调查发现，我国青少年在业余天文学家群体中占有很大的比重，对天文感兴趣、学习天文知识、获得乐趣和认识朋友是我国爱好者参与业余天文学研究的主要动机，这两点与欧美国家业余天文学家有着明显不同。随着我国一系列大科学设备的建成运行，公众科学和业余天文学的潜力需要得到重视。应对公众和爱好者进行积极引导，使他们在学习知识和获得乐趣的同时，能为科学研究作出更大贡献。
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-28 Cooperative journals: 《天文研究与技术》
Abstract： This paper is aimed at separation treatment of low- and high-frequency components in polar motion forecasting and thenimproving time-series predictions. For the purpose, the empirical mode decomposition (EMD) is employed as a filter to extract low- and high-frequency signals from original pole coordinate data. The decomposition of the pole motion observations between 1986 and 2015 from the International Earth Rotation and Reference Systems Service (IERS) C04 seriesillustrates that the low-frequency fluctuations including inter-decadal, inter-annual, Chandler and annual wobbles and shorter-period high-frequency oscillationscan be separated from the observed time-series by the EMD. On the basis of separation, the least-squares (LS) extrapolation of models for annual and Chandler wobbles and for the linear trend are used for deterministic prediction of the low-frequency fluctuations, while the autoregressive (AR) technology is applied to forecasting the high-frequency oscillations plus LS fitting residuals. Pole coordinateforecasts are calculated as the sum of LS extrapolation and AR predictions (LS+AR).We have evaluated the accuracy of our long-term predictions (up to 1 year in the future) in comparison with the IERS official predictions in terms of year-by-year statistics of 5 years. It is shown that the accuracy of the LS+AR methodcan be significantly improved using a combination of the EMD and LS+AR (EMD+LS+AR). Also, the proposed prediction strategyoverall outperforms the IERS solutions. In addition, the predictions are compared with those from the Earth Orientation Parameters Prediction Comparison Campaign (EOP PCC). The comparison demonstrates that the developed schemeis a very accurate approach to predict polar motion. According to this study, it is concluded that polar motion predictions may be enhanced through separation treatment of different time-scale fluctuations and thus such processing seems to be necessary in pole coordinate prediction.
Subjects: Astronomy >> Astrophysics submitted time 2018-02-07
Abstract： In the present letter, with the help of a semi-analytical code we show how taking into account baryonic physics in the #3;CDM model can solve the discrepancy between the numerical predictions of dark matter haloes in the #3;CDM framework and observations from dwarf galaxy scale to clusters of galaxies without the need of different forms of dark matter as recently advocated by [1]. Combining well established results, the paper shows, for the first time, how the flat profiles of galaxy clusters and correlations between several of their main properties, are naturally obtained when baryon physics is correctly taken into account; how the so called ”diversity problem” can be solved and how the challenging, extremely low rising rotation curve of IC2574 can very well be reproduced when baryon physics is taken into account. We therefore suggest that before introducing new exotic features in the standard cosmological model, albeit legitimate, baryonic physics should be treated properly to reach agreement with observations.
Peer Review Status:Awaiting Review
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2021-10-04
Abstract：
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysics submitted time 2018-09-16
Abstract： This paper introduces the inverse dissipation potential into the Newtonian Dynamic equation and studies the motion equations of the objects in the isolated gravitational system. It is found that at large scales it can derive the dynamical equation of cosmic expansion similar to the ΛCDM model and yield the flat rotation curves for spiral galaxy. Different from the usual dark matter models, the derived flat rotation curves are the result of time accumulation rather than the direct action of mechanics. And the Tully-Fisher relationship is also discussed, it is found that the basic constant a0 in the MOND model and the form of the function μ have a clear corresponding physical significance in the model of this paper.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Galaxy and Cosmology submitted time 2018-03-27
Abstract： We study how deviations from spherical symmetry of a system, produced by angular momentum, and shear stress, modify the spherical collapse model, as linear density threshold for collapse of the non-relativistic com-ponent (δ c ) and its virial overdensity (∆ V ), in Einstein-de Sitter and ΛCDM models. We modify the sphericalcollapse model to take account of the shear term and angular momentum term. We find that the non-sphericalterms change the non-linear evolution of the system and that the collapse stops “naturally” at the virial ra-dius. Moreover, values of the linear overdensity parameter and of ∆ V are modified with respect to the standard spherical collapse model.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysics submitted time 2020-03-09
Abstract： We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which had been ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a high-precision orbital period of 0.2224628(2) d (~5.34 hr) and shows KZ Gem to be a double-lined DN. Time series photometry taken from 2016 to 2018 shows a variable double-hump modulation with a full amplitude of ~0.3 mag, along with five Gaussian-like transient events lasting ~30 min or more. Using the light curve code XRBinary and nonlinear fitting code NMfit, we obtain an optimized binary model of the dwarf nova (DN) KZ Gem, from time series photometry, consisting of a Roche-lobe-filling K type dwarf with a mass transfer rate of 2.7 - 7.9 x 10^{-10} solar mass per yr to a large, cool and thick disk surrounding a white dwarf, in an orbit with an inclination of 51.6(+/-1.4) degree. Two hotspots on the disk are demonstrated to cause the observed variations in the ellipsoidal modulations from the secondary star. This physical model is compatible with the Gaia distance of KZ Gem.
Peer Review Status:Awaiting Review
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Astronomy >> Galaxy and Cosmology submitted time 2020-09-09
Abstract： Motivated by recent work on rotating black hole shadow [Phys. Rev. D101, 084029 (2020)], we investigate the shadow behaviors of rotating Hayward-de Sitter black hole for static observers at a finite distance in terms of astronomical observables. This paper uses the newly introduced distortion parameter in [arXiv:2006.00685] to describe the shadow's shape quantitatively. We show that the spin parameter would distort shadows and the magnetic monopole charge would increase the degree of deformation. At the same time, the distortion could be relieved because of the cosmological constant and the distortion would increase with the distance from the black hole. Besides, the spin parameter, magnetic monopole charge and cosmological constant increase will cause the shadow to shrink.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2019-03-25 Cooperative journals: 《天文研究与技术》
Abstract：In a standard model of active galactic nuclei (AGNs), there is a supermassively central black hole surrounded by an accretion disk with the jet coming out perpendic-ularly to the disk plane. Theoretical works suggest that there is a connection between the jet and the accretion disk. To investigate such a connection, people use the cor-relation between the radio emission ( or γ-ray emission) and the broad line emission.However, it is well known that the radio (or γ-ray ) emission is strongly beamed in blazars. In this sense, we should consider the beaming effect when we discuss the jet–accretion disk connection. In this work, we compiled a sample of 202 Fermi/LAT blazars with available broad line emissions. Out of the 202 sources, 66 have known Doppler factors. The corre-lation between γ-ray and broad-line emission, and that between radio and broad-line emission are investigated by removing the effects of redshift and beaming boosting for the whole sample and the subclasses, flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs) respectively. We obtained a strong positive correlation between γ-ray and broad-line emission and between radio and broad-line emis-sion for the 202 blazars; It’s worth noting that the correlation still exists after removing redshift effect. For the 66 sources with Doppler factors, there is also a strong positive correlation between γ-rays and broad-line emission after remov-ing the Doppler factors, as well as that between radio and broadlineemission.Ouranalysissuggestthat1. Therearestrongcorrelationsbetween theγ-rayandthe broad line emission for the whole blazar sample and their subclasses. The correlations exist when the redshift effect is removed for the whole sample and their subclasses,confirming the results by Ghisellini et al. (2014) and Chen (2018). 2. For the 66 blazars with available Doppler factors,a strong correlation between the broad line emission and the Doppler factor is found. The correlation between the γ-ray and the broad line emission exists after the Doppler factor effect is removed. Similar results also obtained between radio and broad-line emission. 3. Our analysis suggests a robust connection between the accretion process and the jet.
Subjects: Astronomy >> Astrophysics Subjects: Astronomy >> Star and Galactic System submitted time 2018-09-12
Dai, zhibin
Szkody, Paula
Kennedy, Mark
Su Jie
Medagangoda, N. Indika
Robinson, Edward L.
Garnavich, Peter M.
De Silva, L. Malith M.
Abstract： We used the light curve code XRBinary to model the quiescent K2 light curves of three low-inclination cataclysmic variables (CVs): 1RXS\,J0632+2536 (J0632+2536), RZ\,Leo, TW\,Vir and the pre-CV WD\,1144+011. Optimized light curve models were obtained using a nonlinear fitting code NMfit and visualized by Phoebe 2.0. The disk model of J0632+2536 shows that one hotspot at the edge of the disk is enough to describe its light curve, while the other two dwarf nova (DN): RZ\,Leo and TW\,Vir require two hotspots. A typical pre-CV model with a weak irradiation effect for WD\,1144+011 can explain its single-hump modulation and the newly observed spectrum confirms its previous classification. The synthetic analyses for the DN clearly indicate that phase zero of the double-hump modulations occurs around the secondary minimum and the primary hump is mainly caused by the hotspot at the edge of the disk. The quiescent disk has a flat temperature distribution with a power index of $\sim0.11$. The disk model of RZ\,Leo implies a truncated disk, supporting its previously speculated classification as an intermediate polar (IP). Except for the IP model of RZ\,Leo, which lacks a component related to the inferred accretion curtain, the models of J0632+2536, TW\,Vir and WD\,1144+011 are consistent with results from the Gaia mission. The derived masses and radii of the secondaries of the three DN are consistent with the semi-empirical relations for CV donor stars, while their effective temperatures are higher than the predictions. Irradiation of the donor stars is investigated to explain this discrepancy."
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2016-11-16
Abstract：本文提出了一种天象厅环境下的座席区设计方法，该方法将天象厅中的观众体验感分为五类，将感官体验量化，分别进行数学建模，然后将五个模型根据比重综合，得到天象厅中体验感的数学模型，对其进行分析得出较优的座席区范围，并引入偏转角变量设计了固定座席区与旋转座席区。并针对天象厅超大垂直面视野设计了一种座椅，该座椅能舒适地为观众提供较大的仰角观看节目
Peer Review Status:Awaiting Review
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2019-11-09
Abstract： In Lorentz violation models, the rainbow model is usually discussed, as the rainbow model can make the energy of a particle have a limit rather than be infinite derived from the Lorentz transformation, which is considered to be necessary in the theory of Quantum Gravity. However, this paper shows that it isn’t necessary to restrict the speed of light to be a constant when we just agree with the next three principles: (1)we can define the time in the whole space with a prescribed clock synchronization, (2)the time-space is uniform and the space is isotropic and (3)all the inertial systems are equivalent. And base on the above three principles and as a result of variable speed of light, we can construct a general coordinate transformation to satisfy the symmetry of inertial systems and construct a non-Lorentz transformation between inertial systems to make the energy of a particle have a limit, which is the same as the rainbow model. In addition, in recent papers, as a test at the ultrahigh energy scale, the rainbow model is used to study the Gamma ray burst, such as the GRB 160509A event, which was strongly suggested that there exists a linear relation between the variable speed of light and the photon’s energy. So we also analyzed the same event and we found that our model also support the same conclusion as the rainbow model and there was some correlation between our model and the rainbow model. In final we briefly discussed how to verify the two models in the future particle’s experiments at the ultrahigh energy scale.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2021-04-14 Cooperative journals: 《天文研究与技术》
Abstract：本文使用快速鲁棒性主成分分析(Fast RPCA，Fast Robust Principal Component Analysis)方法对日冕序列图像中的日冕喷流活动进行检测。检测的基本思路是利用Fast RPCA方法中低秩和稀疏分解的思想与日冕序列图像中有着变化尺度稍小且占比较大的随机变化背景成分、变化尺度较大且占比较小的日冕喷流的特点相结合，以此来实现随机复杂多变的动态背景和稀疏运动目标之间的分离，从而检测出作为前景变化的日冕喷流。采用太阳动力学天文台(Solar Dynamics Observatory，SDO)卫星上大气成像组件(Atmospheric Imaging Assembly，AIA) 观测设备的两组不同时间段、不同波段、不同观测位置的日冕序列图像作为研究对象。研究内容主要包括日冕序列图像的预处理、日冕喷流检测、Fast RPCA方法与帧间差分法的检测结果对比分析。实验结果表明，与帧间差分法相比，Fast RPCA方法能够检测出强度较弱的日冕喷流且提高了日冕喷流检测的准确度。
Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2019-03-31
Abstract： Ideas and theories of turbulence based on modifying the Navier-Stokes equation, to obtain equilibrium and non-equilibrium time-reversible dynamical ensembles relevant to helical turbulence, are presented. Discussions of controlling helicity to control the aerodynamic force, heat and noise are presented, together with the compressible turbulence relevant statistical mechanics analysis. A helical time-reversible system for nonequilibrium dynamical ensemble is constructed. Applications are also remarked.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2020-05-14 Cooperative journals: 《天文研究与技术》
Abstract：对于射电望远镜观测的天文研究，即使很微弱的射频干扰也会导致观测失败或降效。当前射电望远镜台址射频干扰越来越多，需尽快尽量将射频干扰源找到并予以消减。无线定位技术成为查找干扰源时，获取射频发射源准确位置的重要技术手段。基于测距的无线定位算法因其定位精度高，稳定性强而备受关注。本文对几种基于测距的无线定位算法进行研究，分析比对这几种测距定位算法的特点。通过比对，TDOA(Time Difference of Arrival，基于到达时间差)定位算法计算复杂度低，定位精度高；RSSI(Received Signal Strength Indication，基于接收信号强度)定位算法简单易于实现。在此基础上提出了一种基于TDOA定位算法和RSSI定位算法数据融合的测距无线定位算法，该算法在通过TDOA定位算法获得多个初始位置估计值的基础上引入以信号接收强度作为初始位置估计值的权值的数据融合方式，通过线性加权归一化处理获得一个定位精度较高的位置估计值。因信号接收强度易于获得，该数据融合算法在TDOA定位算法基础上增加的计算量较小，且仿真结果表明该算法较单一的TDOA定位算法降低了约20%的定位误差，有效提高了定位精度，便于快速低成本发现射频干扰源。
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Physics >> Atomic and Molecular Physics submitted time 2016-12-10
Abstract：通常的狭义相对论是在庞加莱变换下不变的，它的基本度规为闵科夫斯基时空度规，该度规满足没有宇宙学常数Λ的真空爱因斯坦方程。本文指出：Λ≠0 时的狭义相对论是德西特/反德西特不变狭义相对论。求解Λ≠0的真空爱因斯坦方程，得到这种拓展的狭义相对论的基本度规是陆启铿-邹振隆-郭汉英1974年提出的Beltrami 度规；用欧拉-拉格朗日方程证明Beltrami时空的自由粒子运动是惯性运动。本文求出了德西特/反德西特不变狭义相对论的全部凯林(Killing) 矢量，证明了Beltrami 时空是最大对称性空间。导出来全部守恒量。构造了理论的正则形式，发现了正、负正则能量的色散关系的不对称性；实现了正则量子化，导出了相对论性波方程，从而建立了德西特/反德西特不变的相对论量子力学。简要介绍了通过天文观测原子（或离子）能级劈裂来探测精细结构常数#11;改变的实验。实验结果在4 ∼ 5σ 置信度内否定了庞加莱不变狭义相对论的预言，发现在z ≈ {1 ∼ 3}处αz ̸= α0。由于原子或离子能级的精细结构是相对论量子力学的结果，所以观测实验支持在红移z ≥ 1的狭义相对论量子力学中的Λ修正不可忽略。这是对德西特/反德西特不变狭义相对论的实验支持。是超出现有物理学标准模型的新物理。
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2018-06-01 Cooperative journals: 《天文研究与技术》
Abstract：为了对海外站点和无人值守望远镜进行动态监测，判断望远镜是否处于正常的工作状态，提出了一种联合使用天文定位数据和轴系定位数据对望远镜的运行状态进行动态监测的方法。该方法对观测得到的天文定位与轴系定位数据进行误差计算，对比分析两种数据的误差范围，判断望远镜工作状态。利用该方法对亚太地基光学空间物体观测系统（Asia-Pacific Ground-based Optical Space Object Observation System, APOSOS）项目位于伊朗和巴基斯坦的两台15cm地基光电观测望远镜的观测数据进行检验,结果发现：其中1台 15cm望远镜轴系定位中方位角存在较大误差，误差在上百角秒，设备存在问题。通过对比此设备在国内与国外两地观测数据的误差，确定了出现问题的时间和地点。观测站工作人员对望远镜出现问题的报告印证了分析结论，证明了方法的有效性。
Hits
Hits
Downloads
Comment